ART. 10 



NOTES ON MYCTOPHINE FISHES — PAHR 



33 



Although the three above-considered types have thus all been 

 included in the older species D. rafinesquei Cocco, 1838, it is never- 

 theless desirable to give a more detailed account of the investigated 

 specimens for the purpose of deciding their possible racial relation- 

 ships and the taxonomic priority of their names, in case it should 

 prove possible to subdivide the species, as here understood, into sta- 

 tistical groups of subordinate rank along the lines of taxonomic 

 differentiation followed by Taaning, 1918 and 1928, by the intro- 

 duction of his two new species, D. hoJti and D. mollis. The type 

 specimens considered in the present paper, however, only seem to 

 give further confirmation of the opinion already expressed by the 

 author (Parr, 1928, pp. 131-135) that such subdivision can only be 

 applied to comparatively restricted geographic regions, for the 

 purpose of defining ecological races, but does not enable us to make 

 taxonomic differentiations of general validity and therefore can not 

 serve as a basis for the definition of separate species. 



Table of mcasurefnents 



[In per cent of total length without caudal fin] 



Specimen No _. 



Type of --- 



Total length without caudal fin in mm 



Length of head 



Diameter of eye 



Length of lower jaw 



Length of maxillary 



Greatest height 



Snout to D 



Snout to V 



Snout to A 



442S0 

 M. protoculus 



41914 

 D. theta 



75765 

 D. nanus 



45 30 



28 

 9 

 20 

 19 

 21 

 46 

 44 

 66 



27 32 



10 12 



21 23 



21 23 



22 23 

 74 50 

 44 45 

 65 65 



33 

 12 

 20 

 19 

 23 

 50 

 46 

 62 



The arrangement of the photophores in the three types is shown 

 in the accompanying diagram. 



In D. '•'' theta'''' the upper SAO and the Pol are much nearer to the 

 lateral line than to the ventral series of photophores, while the VLO 

 is considerably closer to the base of ventral fin than to the lateral 

 line, and the PLO is situated about or slightly below midway between 

 the latter and the upper end of the base of pectoral fin. The SAO 

 are placed in an approximately straight and nearly equally spaced 

 series, and the first anterior AO is not elevated. AO 5 + 6. Pre well 

 separated from the posterior AO. According to the definitions first 

 given by Taaning (1918) D. '''■theta'''' should thus agree with D. holti 

 Taaning in the positions of the anterior AO and of the VLO., differ- 

 ing from D. rafinesquei Cocco in both of these respects. 



